What Makes us Depressed – Chemicals or Cognitions?
Depression doesn't just happen, it happens for a reason. Sometimes the reason is evident and sometimes it isn't. When we can't establish the reason, the temptation is to consider depression ‘endogenous' (from within) and we assume therefore it must be due to some chemical imbalance in the brain. But what comes first, the chemicals or the cognitions? Or is it more of an interchange where one affects or influences the other, and have we underestimated the capacity of the brain to heal itself?
Having briefly set the scene I'd like to side step briefly. Judy and Alfredo are regular HealthCentral contributors. When they commented on my post, why depression can make sense, two things emerged. The first was the notion that the way we think could influence our biology and the second was a question about the way our view of depression and other issues tends to be dominated by a particular model of thought. Their helpful contributions set the scene for this Sharepost.
Much of my own learning, and those of psychology students today, is about examining competing influences or 'models'. Some models are more robust and enduring than others, and a common teaching method has always been to compare the strengths and limitations of each to see which ones stack up best in explaining a particular issue and are worthy of further investigation.
Two models in particular currently influence our thinking about depression and therefore its treatment. The first says that depression arises as a result of chemical imbalances (a disease model). The resulting treatment is to try and correct these imbalances with antidepressants. The second says that depression may arise as a result of thinking - that is, the way our thoughts and emotions are affected as a result of specific situations (e.g. bereavement). This can be thought of as a psychological or ‘cognitive' model.
Rather than compete with each other, these models now tend to be seen as complimentary. It is now quite common to find someone being treated with antidepressants alongside say, cognitive therapy. What does this tell us about depression and ways we might see future treatments?
First, I think it tells us that depression may not simply be due to either biochemical changes or ways of thinking. This may be something of a false dichotomy that pushes us to agree with one side or the other. Secondly, we know from functional MRI scans that the way we think causes significant and measurable changes in brain chemistry. With cognitive therapy, these biochemical changes can actually be reversed, suggesting the potential of the mind to reboot or rewire itself.
In cases of situational depression we know that once a person is able to work through the particular problem(s) that cause them distress, their mood lifts. The fact that some people can't identify or recall a particular problem doesn't mean it doesn't exist, so perhaps there is a case for such people to undergo more analytic therapies? My point here is that if thinking is known to cause the biochemical changes that result in depression it could help to explain why antidepressants may help to relieve, but not necessarily cure, depression.
In saying this I am not trying to muddy the waters by dismissing depression as a disease. Depression is a complex and dynamic process that may have more than one cause. Even so, what I think we must explore is the potential of our own brains to correct biochemical changes that cause or influence the symptoms of depression. Armed with the certain knowledge this can happen is hugely encouraging, but we need to know more about what works best and what limitations there may be.
Paquette, V. (et al) (2003) Change the mind and you change the brain: effects of cognitive- behavioral therapy on the neural correlates of spider phobia. NeuroImage 18 401-409. Academic Press. Elselvier.